A safety curtain (or fire curtain in America) is a fire safety precaution used in large prosceniumtheatres. It is usually a heavy fibreglass or iron curtain located immediately behind the proscenium arch. Asbestos-based materials were originally used to manufacture the curtain, before the dangers of asbestos were discovered. The safety curtain is sometimes referred to as an iron in British theatres, regardless of the actual construction material.

The curtain is extremely heavy and therefore requires its own dedicated operating mechanisms. In an emergency, the stage manager can usually pull a lever backstage which will cause the curtain to fall rapidly into position. Alternatively, heat-sensitive components can be built into the rigging to automatically close this curtain in case of fire. Finally, it may be released electronically by a building's fire control system if any alarm box is operated. It can also be flown in and out, as regulations in some jurisdictions state that it must be shown to the audience, to prove its effective operation, for a certain amount of time during every performance. This usually occurs during the intermission.

In smaller theatres, a safety curtain is not usually required. Specifically, most United States building codes only require a fire curtain in theatres with a stage height of more than 50 feet (15 m). [1] The heavy, flame-retardant house tabs can provide some degree of fire separation.

In the UK, it is a requirement that a safety curtain must be fully down within the proscenium opening within 30 seconds of being released. The Theatre Royal, Drury Lane was the first theatre to feature an iron safety curtain.[2] Several other serious fires, notably that at the Theatre Royal, Exeter in 1887, led to the introduction of safety curtains on a wider scale.

The safety curtain can be combined with other safety devices, such as:

Smoke pockets - are steel channels located at either side of the proscenium arch that the safety curtain travels within to create a physical barrier between the auditorium and the stage. The safety curtain is not intended to create an air seal but rather prevent material from falling from the stage house into the audience.

Fire doors - heavy, fireproof doors that are designed to automatically close any doorway onto the stage in the event of a fire. These doors are usually on a slightly pitched track, and are rigged in a way that causes them to automatically close when heated to a certain temperature.

Smoke doors or stage lantern - vents above the stage which, when opened in case of fire, will draw smoke out of the auditorium and up out of the roof of the theatre, enabling safer evacuation of the audience. The vents are often attached to compressed springs, so that when activated, they will stay open.

Drencher or deluge system - a large reservoir of water stored above the stage which, when released in case of fire, will flood the stage in an attempt to extinguish any flames. This type of system can be problematic, as water interacting with onstage electrical circuits can cause fire.

Water Curtain- a system similar to the deluge system, except instead of having the water drench the stage itself, the water flows from sprinkler heads or other nozzles directly in front of the proscenium to prevent sparks from flying off the stage or to extinguish any burning material (such as a set) which may fall through the proscenium.

In the event of a fire, the use of smoke doors and fire curtains means that the stage area effectively functions as a chimney. The heated air rises and leaves through the smoke doors, and this puts the building into negative pressure, which in turn draws fresh air in through any open exit doors. Patrons waiting to exit will have fresh breathing air until the exit doors close. The exit doors which open out will be drawn closed tightly by this draft once they are no longer held open by evacuees. Once the doors are closed, the fire loses its oxygen source. If the doors are then opened again, a backdraft can occur.